mineral

Tumbled smoky quartz fragments

Smoky quartz, silicon dioxide (SiO₂), quartz variety colored by irradiation-related color centers

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, conchoidal fracture, and trigonal crystal structure; these pieces are polished or naturally worn, translucent gray-brown to nearly black, with internal fractures and inclusions.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks, commonly during late-stage cooling; specimens may range from Precambrian to younger geological ages. The photographed pieces appear tumbled or broken rather than naturally crystal-terminated.

Uses & applications

Used as an ornamental and lapidary stone, in cabochons, carvings, jewelry, and mineral collections; quartz also has major industrial uses in glass, ceramics, and electronics.

Geological facts

Smoky color can result from natural radiation acting on aluminum impurities in quartz. Heating may lighten or remove the color, while some very dark material is marketed as morion.

Field identification & locations

Identify by hardness, glassy luster, conchoidal fracture, and inability to scratch it with a steel knife; glass is commonly scratched by quartz. Common sources include Brazil, Madagascar, Switzerland, the United States, and Scotland.